Herbal Cat Flea Remedies Are No Safer Than Conventional Treatments
I was looking for safe and natural home treatments for the notorious cat flea (my cat does not have fleas 🙂 ). I thought about herbs. Herbs after all are plants from the natural world. They aren’t manufactured in the laboratory therefore one would think that they would be less toxic. My initial research in a reference book1 did not refer to potential toxicity but rather that certain herbs listed below may help in the fight against the cat flea.
The reference book states that “certain aromatic herbal powders can be applied to the cat’s coat: as always, read the accompanying instructions carefully”. The book then lists some herbal remedies such as Pennyroyal, eucalyptus, wormwood, rosemary and rue.

Apparently, Pennyroyal has a long history of combating fleas on people as well as animals. The plant grows quite easily in most parts of the world, with the American pennyroyal seeming to have identical properties to its Old World relative. Eucalyptus is another aromatic plant, in this case a tree, which is often incorporated in herbal flea treatments. Wormwood, rosemary and rue are other herbs considered a value in the fight against fleas.
My research, online, however immediately threw up doubts about the use of these herbal treatments because of their toxicity to cats. For example, on the pet MD.com website there is a page entitled “Pennyroyal Oil Poisoning in Cats”. Pennyroyal oil is derived from the herb, as I understand it, and they say that it is frequently used in flea powders and sprays. They also say that it can be toxic to cats particularly when ingested. The symptoms are extensive. I can only think that this herb must be avoided because if there is any doubt about the safety of a product it should be avoided in my opinion.
As for eucalyptus, ASPCA state, apparently, that eucalyptus oil is toxic to dogs cats and horses. Well, once again we have to exclude eucalyptus because there are doubts about its safety. In fact – and I have not read the ASPCA page – the plant itself appears to be poisonous to cats in addition to the oil which must be extracted from the plant. Cats are not able to properly metabolize the compounds within the oil leading to a dangerous accumulation of toxins.
Of course, we have to remember that when dealing with fleas people are applying treatments to the cat’s coat from where it is almost bound to be ingested by the cat so any treatments must be 100% safe.
As for rosemary, this herb contains a “highly volatile unsaturated hydrocarbon”. This hydrocarbon2 is easily absorbed through the skin and of course it would be ingested when the cat licks her coat. It seems that large amounts of this hydrocarbon can build up in the cat’s liver because it cannot be broken down by a cat’s enzymes. This can lead to poisoning. Rosemary is an effective flea repellent because they don’t like the smell but, as mentioned, it would seem to be too dangerous to use; certainly from my perspective it is.
My initial assessment is that herbal remedies are probably not much safer than the potentially toxic over-the-counter flea treatments one can buy on the Internet or from your veterinarian. In fact they may be more dangerous because at least with conventional treatments (please buy them carefully as some are horribly toxic) there are detailed instructions. It is harder to come by instructions on how to use herbs as flea remedies.
The best way to deal with fleas is to be proactive and to constantly check whether your cat has them with a flea comb and then take steps always to prevent your cat harbouring fleas. It’s about being holistically proactive and vigorously concerned about the potential that your cat has of harbouring fleas. Also remember that nearly all cat flea treatments are insecticides which are nasty, toxic chemicals. Great care in their use must always be exercised.
Note: If you know of a safe herbal cat flea remedy please tell me in a comment and disagree with me.
Refs:
- The Natural Health Cat Care Manual (page 66)
- terpenoids